Electronic apparatuses including cell phones and personal computers have been downsized and light-weighted in recent years, and an electronic apparatus accommodated in a double-backed housing has become popular, i.e. a movable housing is mounted to a stationary housing in a closable manner. The opening and closing device employed in such a double-backed housing thus needs to be inexpensive and positively closed or opened.
A conventional opening and closing device is described with reference to FIG. 11-FIG. 14D. Sectional views among these drawings enlarge the radial direction of a stationary cam and a movable cam for illustrating the relation between these cams more understandably.
FIG. 12 shows a sectional view of a conventional opening and closing device, and FIG. 13 shows an exploded perspective view of the conventional opening and closing device. Conventional opening and closing device 20 includes cylindrical stationary unit 1 made of metal, stationary case 2, and cylindrical stationary shaft 3. Stationary unit 1 has a pair of stationary cams 4 grooved on its entire outer wall, and stationary shaft 3 has stationary case 2 fixed at its left end as well as stationary unit 1 fixed at its center part.
Conventional opening and closing device 20 includes ring-shaped movable unit 5 made of metal and cylindrical movable case 6. Movable unit 5 has a pair of pin-shaped movable cam 7 protruding on its inner wall, and a pair of protrusions 5A protruding outward on its outer wall. Protrusions 5A are inserted into grooves 6A, so that movable unit 5 can be moved along the axial direction with respect to movable case 6, and can be rotated along the rotational direction together with movable case 6.
Movable case 6 has stationary case 2 mounted rotatably at its left end opening, and stationary section 2A of stationary case 2 protrudes leftward. Stationary shaft 3 extends through movable case 6 and its right end is rotatably mounted to an outer lateral face of movable case 6 by retaining ring 8.
Spring 9 shaping like a coil seats in somewhat compressed manner between the right lateral face of movable unit 5 and the inner wall of movable case 6. Spring 9 urges movable unit 5 toward stationary unit 1 placed on the left side. Cylindrical reversing unit 10 made of metal has reversing cam 12 at its left end, and reversing cam 12 has bumps and dips. Ring-shaped releasing unit 11 has releasing cam 13 at its right end, and cam 13 has bumps and dips. Reversing unit 11 is mounted to stationary case 2 in a movable manner along the axial direction, and releasing unit 11 is rotatably mounted to stationary case 2.
Conventional opening and closing device 20 also includes pushing unit 14 having pushing cam 15 at its right end, and cam 15 has bumps and dips. Helical spring 16 is somewhat twisted, and is anchored at its first end to releasing unit 11 and at its second end to pushing unit 14. Pushing unit 14 is mounted to the left end of stationary shaft 3 movably along the axial direction, and protrudes from stationary case 2 leftward. Opening and closing device 20 is thus constructed.
Opening and closing device 20 discussed above is, for instance, is employed to a cell phone of which perspective view is shown in FIG. 11; stationary section 2A of stationary case 2 is fixed to stationary housing 22, where operating section 22A having a plurality of keys on the top face and audio-input section 22B, namely, a microphone, are formed. Movable case 6 is fixed to movable housing 23 where display section 23A such as an LCD and audio-output section 23B such as a speaker are formed.
Pushing unit 14 has push button 24 mounted thereto, and button 24 protrudes from a lateral face of stationary housing 22. Opening and closing device 20 supports movable housing 23 in a closable manner with respect to stationary housing 22, thereby forming an electronic apparatus such as the cell phone shown in FIG. 11.
In the foregoing structure, when movable housing 23 is closed with respect to stationary housing 22, opening and closing device 20 acts in the following manner: As FIG. 12 and FIG. 14A show the actions of the cams, reversing cam 12 protruding from stationary cam 4 toward movable cam 7 has a slope on its right side, and movable cam 7 elastically urges against the slope, and movable unit 5 is urged by spring 9 rightward, i.e. closing direction. Urging force along the closing direction thus acts on movable housing 23 to which movable case 6 is mounted, so that movable housing 23 can keep closing.
At this closed status, a push of button 24 placed on the lateral face of stationary housing 22 prompts pushing cam 15 of pushing unit 14, to which button 24 is mounted, to press releasing cam 13. Then releasing cam 13 rotates rightward while it compresses helical spring 16, so that releasing cam 13 gets out of the lower end of reversing cam 13 as shown in FIG. 14B, thereby moving the reversing cam 12 downward.
Movable cam 7 urged by spring 9 elastically urges against the slope on the left side of stationary cam 4 and rotates leftward, so that movable unit 5 is urged leftward, i.e. opening direction. This urging force prompts movable housing 23 to open. As shown in FIG. 14C, while movable cam 7 urged by spring 9 elastically slides on the slope on the left side of stationary cam 4 and rotates leftward, movable unit 5 and movable case 6 are urged leftward, i.e. opening direction, so that opening force is applied to movable housing 23. As a result, movable housing 23 opens at a given angle, e.g. ca. 160 degrees, with respect to stationary housing 22. At this time, a release of a finger from push button 24, namely a release of the pushing force from pushing unit 14, prompts releasing cam 13 urged by helical spring 16 to rotate leftward and push reversing cam 12 upward.
As shown in FIG. 14D, releasing cam 13 and pushing cam 15 return to their places shown in FIG. 14A, and reversing cam 12 pushed by releasing cam 13 moves upward and returns to its original place. In other words, in addition to a manual opening/closing operation of movable housing 23, a push of pushing unit 14 prompts releasing cam 13 to rotate and reversing cam 12 to move vertically, i.e. along the axial direction, whereby movable cam 7 elastically slides on stationary cam 4 for opening movable housing 23 with one-touch. As a result, a one-touch opening operation can be done.
Prior art related to the present invention is, e.g. unexamined Japanese Patent Publication No. 2004-150575.
The conventional opening and closing device discussed above; however, needs elaborate machining. To be more specific, when reversing cam 12 moves along the axial direction, movable cam 7 elastically urges against only stationary cam 4 for producing the opening force. Grooved stationary cam 4 should be thus formed almost on the entire outer wall of stationary unit 1 so that a pair of movable cams 7 formed on the inner wall of movable unit 5 can elastically slide on grooved stationary cam 4. As a result, the elaborate machining, which takes time, is required for manufacturing the stationary unit 1, and it results in an expensive mechanism.